


Probability Engine

by grandilloquism



Category: Harry Potter - J. K. Rowling
Genre: Alternate Universe, Alternate Universe - Steampunk, Explosions, M/M, RS Games 2012, Steampunk, dubious magical systems, technomancy
Language: English
Status: Completed
Published: 2013-04-02
Updated: 2013-04-02
Packaged: 2017-12-07 06:24:43
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,877
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/745324
Author URL: https://archiveofourown.org/users/grandilloquism/pseuds/grandilloquism
Summary: <blockquote class="userstuff">
              <p>Remus is an Unspeakable and Sirius Black is his latest assignment. Sirius is just trying to keep his world from falling down around him.</p>
            </blockquote>





	Probability Engine

**Author's Note:**

> Written for the Neil Gaiman prompt, "There was once a young man who wished to gain his Heart's Desire." for the RS Games 2012. Beta'd by Nathaniel_hp.

The place was crowded even for a subspace club. The vibration of the thaumatelectric engine felt even over the heavy bass of the music. It wasn't Remus' usual scene, especially when one considered the combination of cheap thaumatics and alcohol. Nevertheless, his first stop was the bar, counting on the aggressively pink drink in his hand to be better camouflage than his perfectly unremarkable clothes, and relying on his werewolf metabolism to render the alcohol content a non-issue. It would take a much larger expense account than his to interfere with his perceptions.

It was an essential, but low-risk sort of op: get eyes on a Ministry asset that went through handlers like tissues. Apparently, someone high in the Department of Mysteries thought the resident werewolf-magician was the best man for the job. Remus didn't feel much either way about it, except for the anticipation of the challenge, and the niggling discomfort of being in a pocket of subspace that could snap shut and trap them if the engine holding the door open had been even slightly miscalibrated.

He moved nimbly through the dancing throng, eyes moving, nose cataloguing and dismissing scents, searching the room for the only two relevancies: the asset and potential threats.

The room itself was perfectly square, about half the size of a Quidditch pitch, ceiling, floor, and walls all painted matte black, with areas separated by sheer curtains in a rainbow of hues and a circular bar situated in the very centre. There was one door and dozens of hiding places.

But Remus had his senses and was already beginning to pick out one particular scent in a sea of them: engine oils, sandalwood and mint over male skin-sweat. He tracked it from near the bar, making slow, widening circles of the floor. He followed his nose, eyes flickering restlessly from face to face; until they settled on the right one. A face made of angles: sharp cut of the cheekbones to an angular jaw, straight line of the nose and precise cut of the mouth, loose black spill of hair shaggy and sweat slick from exertion.

Gods, but the man was attractive. White shirt nearly transparent, rucked up over his navel by the hands of a man not so much dancing as shamelessly rutting behind him. Sirius Black was laughing, head thrown back, throat exposed, hips keeping time to the music in trousers that failed to hide his arousal.

Excuse him, but Remus wasn't going to let his asset, one of the greatest thaumatelectric minds in the world, be used as a tool of sexual gratification on a dance floor in a no-name, back alley subspace club, in full view of anyone who cared to look. Without even upsetting his drink Remus navigated the crowd and had the over-eager suitor stumbling away with a sharp jab to the side and a bite of thaumatic shock to the neck. It happened so quickly and was covered so well by the loud music and jostling crowd that Sirius' expression was one of utter puzzlement when he turned and caught sight of Remus.

"What did you do with Johnny?" Sirius was practically shouting to be heard, but Remus still found himself having to move closer to catch the words. Remus smiled, more flirtatiously than was his wont, but he felt he could hardly be blamed with all the arousal cues Sirius was giving off. When he tugged gently on his arm, Sirius let himself be led out of the club.

There was a moment of disorientation as they passed through the door-- actually a small hole ripped in the fabric of space itself --and out into the world. It was raining in London, a gentle mist that just wet the pavement. "I didn't need saving back there," was the second thing Sirius Black ever said to him.

"I noticed." Remus' smile was wry. "But your partner needed a chance to, ah, cool his head. Besides, think of all the sensibilities you were offending. Imagine the headlines if anyone had recognized you: Disgraced Black Scion, Indecent on Dancefloor."

Sirius' eyes were quite suddenly shuttered. "You're here to keep tabs on me."

"I am." He saw no point in denying it.

"By my family?"

"Only peripherally. In the way that most of the Ministry can't help but be related to you."

"You work for the Ministry."

Remus couldn't point to the last time he had been in such a good mood. "And that's why they call you a genius. Astute deductions like that, how can the rest of us compare?" His voice had remained level, deadpan, but he caught the twitch at the corner of Sirius' mouth, the rekindled warmth in his eyes.

"Shut up. I don't even know who you are, you can't just pull a guy off the street--"

"Please, I pulled you off of a dancefloor, and as an agent of the Ministry handling a lawbreaker--"

"A what?"

"--you could be a lot worse off than getting an escort home. And yes, it is still illegal to engage in sexual acts in a publically zoned subspace. I imagine the charges would be enough to see you in a holding tank until morning, when they'd be dismissed on lack of evidence. Still, it'd make for an uncomfortable few hours. I would, of course, be perfectly happy to simply see you to your flat, providing you drop in on the Ministry tomorrow and give us that report you've been promising."

"Who are you, even? Besides a complete cock-blocking bastard."

"I'm Remus Lupin. I'm your new handler."

X

They took an automated cab to Sirius' building. Remus had ample time to discover that the man switched between unmoving stillness and almost spastic activity, with seemingly no middle setting. It was in a fit of drumming fingers and tapping toes that Sirius blurted, "So you're a werewolf." When Remus looked at him sidelong, he saw he was smiling. "They don't just call me genius for the ego boost."

"And so modest, too."

"But you are? I mean, a werewolf?" He apparently interpreted Remus' single raised eyebrow as an affirmative. "So if I tried to loose you in a crowd--?"

"Not advised."

"And if I happened to use some monkshood?"

"If you happened to use a dangerous, controlled substance against an agent of your government? Then I'd remind you I'm a more than competent wizard."

"And so modest, too," Sirius said, a crooked smile hooking up one side of his mouth. Remus was going to kick him, and it was going to be his own fault. Give me patience, he requested of the universe.

"I saw the readings we managed to get before you sabotaged our equipment."

"You mean the ones your spy sensors took before I defended my intellectual property?"

"The very same. I was curious about the range of fluctuations. From 67, stable subspace portal, to absolute zero, magical neutral, in less than twenty seconds? It's impressive."

"Impressive is sort of what I do." Sirius had his face turned from him, looking out the window at the city. There had been more than boasting in his voice, something bitter, out of place.

"From what I understand," Remus began, voice soft in an effort to draw Sirius out, "it takes hours to properly cycle down a subspace portal, and that isn't likely to change soon, if ever. So what I have to think is, could someone create something to bypass the process? Interfere with the engine, somehow, or impose a localised environment in which a portal couldn't exist?"

"Without the engine going into catastrophic failure and killing everyone in a fifty-metre radius? Sounds difficult."

"Yes, I imagine so. Only, think how well it would explain those readings we took from your workshop."

"Fascinating theory, really. I'd love to discuss it, but I'm afraid this is me." He gestured out the window to where they were pulling up to a tall, dark-fronted building. The cab had barely stopped in front of it before Sirius was up, out and slamming the door in Remus' face. He was prepared to let it go, to call it a night and a successful first meeting and come back the next day to frogmarch Sirius to the Ministry if he had to, if not for that peculiar scent Remus got a nose-full of just as the door closed. Ozone, saltwater, and hot copper.

"Sirius!" He was shouting even before he had the door open. "Sirius!" Outside the cab the smell was strong enough to make him sneeze. He got a hand on the man's shoulder and was dragging him back, not shy about his strength, when the smell intensified. Remus doubled over in a fit of sneezes, eyes streaming. His ears popped, and he had just enough time to pull Sirius to the other side of the cab and cover him with his body before there came the shriek of metal complaining, loudly, and then a muffled fwomp.

X

Remus regained consciousness to the odd pop-pop-pop of his ears healing damage from the percussive force of the explosion. Sirius was stirring under him, and in the distance he could hear sirens headed their way. One thing became immediately apparent: either Sirius had better wards than half the Department of Mysteries, or it had not been one of the thaumatelectric experiments in his home workshop that had caused the explosion. And while that still left a range of innocent explanations, Remus couldn't help but be suspicious of the timing. Not to mention the smell that still hung in the air, that mix of metal and magics.

Sirius' eyes were unfocused, blinking owlishly, and a cut near his hairline was bleeding sluggishly. Remus picked a grease pencil from out one of his coat's inner pockets and drew a careful line of healing runes from the fragile skin in front of one ear, across Sirius' brow, and to the skin of the other ear. It flashed amber light and Sirius' eyes gained focus, the cut at his temple scabbing over and then fading to new scar pink.

Remus backed up into a crouch next to him, wanting, but not quite daring, to wipe the spent runes from his skin with a thumb. Instead he handed Sirius a handkerchief, produced from yet another inner pocket.

Sirius stared at it blankly for a moment, before accepting it and looking back up at Remus. "The fuck just happened?"

"Some sort of explosive device. Likely a thaumatic charge, remotely detonated."

Sirius seemed to grasp no concept of what handkerchiefs were for; Remus' stayed grasped loosely in one hand. "They were waiting for me. You just saved my life." He still sounded a little shock-ey, and Remus wished dearly for a little chocolate to help try and focus him.

"Don't be dramatic. I doubt you would have died."

Sirius was picking himself up from the pavement, dusting off his trousers. "Excuse me, I think I'm allowed to be as dramatic as I like after someone tries to kill me." He paused, then, stiffly, awkwardly, said, "Thank you. For the rescue."

"You should thank the cab." It had put enough iron between them and the blast that they'd only truly felt the physical effects, not the magical.

"I'm not thanking a pile of scrap that's still waiting for us to pay it."

Remus eased out of his crouch, opened the closest car door and fed a single gold coin into the slot, which made a pleased whirring sound. The door closed itself, and the cab drove off, its light flicking on, seemingly none the worse for wear. Meanwhile, the sirens were drawing closer. Sirius finally used the handkerchief in the spirit it was offered, but mostly just managed to smear grease and blood across his forehead.

"How do you feel about pancakes?" Remus asked, as he began walking.

Sirius merely watched him for a beat, then scrambled to catch up. "What?"

"Pancakes," he repeated. "We've just had a shock-- I was thinking we could use the sugar."

X

It was coming on four in the morning, but that just meant they were seated quickly. Remus ordered for the both of them, not just pancakes, but eggs, bacon, sausages and toast as well. When the waitress, a sleepy-eyed student type prone to reciting human anatomy under her breath, left them, it was Sirius' cue to start in with his questions.

"Don't you work for the Ministry? I thought they frowned on fleeing crime scenes?"

"The Ministry is a many headed monster that delights in damaging its other heads in whichever way it can. It was MLE coming to investigate your bomb. Trust me that it was best to get out of their way."

"And why is that?"

"Because right now the Aurors have an unexplained explosion and no reason to be especially interested in it. So when my department puts in a request for the case in a few hours' time, they'll have no reason to deny it."

"Because they won't suspect the Unspeakables are involved. That's kind of tricksy."

"Would you believe 'tricksy' is on my resumé?"

"Just after 'has a lot of pockets' and before 'ability to be glib under pressure?' Yeah, I can see it." Their drinks came, and Remus watched as Sirius ripped the tops off three packets of sugar and added them to his tea. "So what do we do now?" he asked, stirring the gently steaming liquid with a finger.

"What do you mean?" Remus sipped idly at his own tea.

"We still have hours until we can get the Aurors' report on the explosion, right? So what do we do in the meantime?"

Remus had a list, actually. Very little of which could be discussed where it might be overheard. Sirius didn't seem pleased when he told him as much.

X

Despite the promise of dawn as they left the diner, the air was noticeably cooler. Sirius, in his thin t-shirt, was shivering inside of a minute. Remus drew the grease pen from its pocket before offering the jacket to Sirius.

"So we can take turns shivering to death?" he asked, but shrugged the extra layer on willingly enough.

Remus rolled his sleeve up to mark a temperature stasis rune on the skin just above his inner elbow -- heating and cooling magic could have unpredictable results on werewolf biology. Sirius silently offered his own arm and Remus' eyebrows went up. The rune-chains Sirius would need to build to combine magics and machine were infinitely more complex than the little warming charms Remus obligingly drew on each of Sirius' wrists.

"It's engines more than people," Sirius explained, peering closely at Remus' work. "As far as my magic's concerned, anyway." He glanced up. "Now will you tell me what we're doing?"

Remus led down the silent streets. "We're going to see a friend of mine."

"I thought you said the DoM couldn't do anything until the offices opened."

"I did say that," Remus agreed. "I, however, did not say that all of my friends were on the same side of the law."

"Why, Agent Lupin," Sirius said archly, "you do keep bad company, don't you?"

Remus gave him a meaningful look. "The worst." Whatever else he wanted to say about influences, it was true that he had steadily been leading them downmarket ever since they left Sirius' building.

"I swear," Sirius said, when he saw the street they were headed towards, "for a government agent you sure are fulfilling a lot of my secret life of crime fantasies. Midnight assignations in Knockturn Alley?"

Remus snaked an arm around Sirius' middle, absolutely because it was vital to his safety and not at all because he wanted to. It did, after all, not hurt to have a friendly werewolf draped across you, personal safety-wise.

"Hello," Sirius commented, looking down at where they walked pressed hip-to-hip.

"We were drawing attention." He could, at least, lie with a straight face.

"Yes," Sirius agreed, gesturing widely to the empty street. "Obviously all eyes are glued."

"Shut up."

"Or what? You'll cuddle me to death?"

"Just think of me as your human shield," Remus said, teeth gritted.

"If I do, will you still respect me in the morning?"

"At which point did I lose the ability to convincingly threaten you, do you think?"

Sirius was grinning, sharp and bright and so handsome it twisted something in Remus just to look. "Oh, after the pancakes, definitely. You can't be frightened of a man you've watched eat chocolate chip pancakes."

"Lies and slander," Remus protested, guiding them to a door marked out by a gilt metal flower, shaped into a door-knocker. Remus knocked. Ominously, the door creaked open.

"Gods," Sirius huffed, "whose evil lair are you leading me into?"

X

Lily Evans wasn't precisely a criminal. It was simply that she preferred to work around the law rather than inside of it. What exactly it was that she did was harder to explain, outside of the generic. She fixed things. Whatever that entailed. She was good at it. Remus considered it the darkest moment of his career, the day she had turned down his offer to join the Department of Mysteries.

She looked the same as always: puckish, with her short red hair tufting up around her head, tilt-tipped nose, and green eyes. Four years of acquaintance, of popping in at all hours, and Remus had never once caught her sleeping; he was beginning to suspect she didn't. She was standing at the top of a flight of rickety stairs, face lit by a device emitting clear blue light, insides exposed and trailing wires, that she had gripped in her hand.

"A bomb goes off in London, and Remus Lupin is at my door not two hours later." She squinted through the gloom. "Who's your friend?"

"Lily, this is Sirius Black. Sirius, Lily Evans."

"Of course it is," Lily sighed. "I suppose you both better come up."

 

The upper floor was one large room, divided into a sitting area to talk to clients and a laboratory arcana to do her spellwork. None of it was in great repair, but Remus supposed it didn't pay to have nice things in Knockturn Alley.

"Tell me what happened," Lily said, leaning forward with her elbows on her knees, her face unreadable.

He told her about the smell, magic and super-heated metal, about the relative weakness of the charge, its inability to move through iron. It didn't take much more than a minute to go through all he knew, and Sirius stayed uncharacteristically quiet for the duration.

Lily very slowly leaned back into her chair. "What time was it? When the bomb went off?"

"A little after three. So you do--"

"It was 3:26," Sirius corrected. "My watch broke." He held his wrist up so they could see the face, hands frozen.

"That's interesting," Lily said, then pointed a finger at Remus. "What were you going to say?"

"You do think it was a bomb, then, not an equipment malfunction or something?" He wanted to be very clear on that point.

"I think it was both." She smiled at the face Remus pulled. "But I'll explain myself in a minute. Sirius, let me see your watch." He passed it to Remus, who had to stand to pass it to Lily. He stayed standing as Lily examined the watch, circling around the sofa to stand behind Sirius.

He found it a comfortable place to be, between Sirius and the door, with convenient mirrors opening up his view of the room, allowing him to watch Sirius' face. He did not even try to convince himself it was a purely tactical manoeuvre. He was invested. In less than five hours Remus was already invested. In an asset.

"Thaumatic battery powering the clockwork. It's a tidy mechanism. Yours?" Lily asked. Sirius nodded confirmation. "Lovely. Impractical, of course, but it's a beautiful design. I imagine the static from the bomb shocked it. May I?" She gestured to the second half of the room, indicating the watch.

"If you like."

Lily settled at a tall, rubber-topped table with a box of tools, none of them bigger than a pencil, and a stick of charcoal. As she worked, she spoke, "About your bomb, Remus."

"You mean the bomb that is also an equipment malfunction?"

"That's the one, yes." A smile tilted up the corner of her mouth he could see. "An instability rune on a cheap bit of thaumatics, tied to a detonator. The thing is, there have been others. New York, Mexico City, Melbourne, Johannesburg, and, now, London."

"Five cities."

"That's right. Five cities, five non-lethal bombings, and five thefts."

"Fuck," Sirius swore. "Fuck."

"So my question," Lily slanted a look in Sirius' direction, "is what do you have in your flat that's worth stealing?"

Sirius was cradling his head in his hands, body held still and stiff as a statue. Remus set his hand on Sirius' shoulder and felt it marginally relax. "One thing comes to mind."

Remus absolutely did not tense up, but he couldn't keep the edge from his voice. "This wouldn't involve that 'fascinating theory' of mine? The one you implied couldn't possibly exist?"

"It's a portal killer," Sirius admitted, voice low and rough. "I never intended to build it, but," he barked a humourless laugh, "I suppose it was inevitable. I tested the prototype last week. And it worked. It worked really well. It--" He looked up, over towards Lily, who seemed steadfastly engrossed in her tinkering, then up into the mirror to meet Remus' eyes. "I, gods, it wasn't even that hard. Just a catalyzing agent, make the engines cycle at a level they can't sustain, the thaumatic output increases tenfold and it breaks the rune-chains. They crumble. You open up the casings and it's just dust inside." His pale eyes were huge in his face, overbright. "Seventeen seconds. If someone had been inside--"

"There are protocols," Remus said. "It's always possible to open new doors."

Lily was less sympathetic. "You aren't Oppenheimer, and this isn't the atom bomb. You screwed up. You'll fix it." She was smiling, holding Sirius' watch up by one end so they could see the pale thaumatic light shining from the face, indicating the battery was working again. "I'll even help you."

X

Lily kicked them out, smiling, though. Chiding them to get some rest while she tidied their messes for them. They headed to Remus' flat, since Sirius' was the subject of active investigation. It was a bit far to walk, but Remus always thought dawn was the best time to be out, and it gave him ample time to think things over. He was still trying to put the narrative together.

Sirius had built and tested his portal killer in his lab at Black Thaumatics. Remus had the energy readings to back that up. Sometime between then and the day before he had, for whatever reason, transferred it from the Black 'Mat building to his own flat. Meaning whoever had stolen it had to know it had been moved, quite apart from knowing it existed in the first place. Remus was trying to think of a tactful way of asking Sirius when he had last seen his brother, a member of a small but vocal group that believed thaumatelectrics, the combination of magic and machines, was highest blasphemy, but was saved when Sirius broke the silence that had prevailed for the last few blocks.

"I talked to Regulus yesterday." He looked up at the lightening sky. "Day before yesterday," he corrected.

Remus put special effort into sounding as non-judgemental as was possible for him to sound. "Oh? How did that go?"

Sirius snorted. "He was very pleased. Practically starry-eyed over his big brother's accomplishments. I believe his exact words were, 'You're a shame to our parents' memory and you deserve what you have coming.' So, you know, good times all around."

Remus winced. "I'm sorry."

He waved an airy hand. "Don't be. It's nothing he hasn't been repeating for the last seven years. I became principal shareholder in Black 'Mat when our parents died. It didn't matter that he got everything else -- half the money, most of the property. He's been buying up whatever shares he can ever since I opened the thaumatelectrics department."

"Can he hurt you that way?"

Sirius jabbed a thumb into his chest. "I own about 52% percent of the stock. Even if he managed to buy everything else, and he won't, because nearly every Black or Black relation in the world owns a piece of Black 'Mat and they never agree on anything, he'd only ever be an annoyance. Gods, I don't even-- that was a 'matlec bomb they used, Remus. What is he doing?"

"It's likely he sold the information to whoever he thought would cause the most trouble for you." Remus had never claimed at being good with comforting people. He couldn't even look at Sirius, because Sirius was wearing an expression like he was watching his world crack and fall around him. Remus gave into impulse and wrapped his arm around Sirius, and this time, the gesture meant nothing but comfort.

X

Remus gave Sirius his bed and made up a cot for himself on the sofa. He spent nearly an hour tracking the sun's progress across his ceiling before resigning himself to sleeplessness, showering and dressing for the day.

It was half eleven and Remus was rereading his, laughably underinformed, file on Sirius for the nth time when Lily came knocking at his door. She was holding something that looked like a cross between a pair of copper shears, a television aerial, and a turkey baster.

"Is that it?" he asked, surprised and annoyed but mostly very, very relieved.

"Shocked the hell out of me, too. Went straight to Mundungus. He sent me over to a bar near King's Cross-- barmaid's girlfriend had overheard a conversation between an American gentleman and a man that could match Regulus Black's description. Very suspicious, but she's not much for the MLE. Didn't mind telling me, though." Lily flashed a brilliant smile. "Said he was staying at the Leaky Cauldron, which was a spot of luck. Tom owes me a favour-- he set the fire alarm off, gave me a chance to get this little beauty." She handed the portal killer over to Remus.

He would have liked to study it, but the thaumatic vibration it gave off was enough to set his teeth on edge. He placed it carefully on his coffee table and turned back to Lily. She had, in the time his back was turned, adopted a sombre expression.

"Remus," she said. She opened her mouth to continue, but Remus cut her off.

"I know." He passed a hand over his face. "Believe me, I know."

"You saw him, earlier. If I could tell--"

"I know," he repeated. "I-- I'm working on it."

"Okay, then. Good. As long as you're-- good." Her smile was small, but sincere. "I like seeing you with someone, Remus."

"I like you, Lily, but we are not about to talk about my feelings."

"Oh, gods." She was fighting back laughter, both hands held palm out in surrender. "Okay. Alright, fair enough. I'll leave now, so long as you promise not to stew in your own manpain."

"Do you want a written promise, or is a verbal contract enough?"

Lily grinned, impish, eyes bright. She raised an eyebrow. "Cross your heart and hope to die?"

X

Remus had left a note, but he was still surprised when he let himself back into his flat and found Sirius waiting for him on his sofa. The portal killer, Remus couldn't help but notice, had been reduced to its component parts. If their position on the floor was any clue, Remus could guess that the method involved had been rather less sophisticated than the one used to put it together. He graciously pretended not to notice as he crunched pieces of machinery under his shoes.

"You left," Sirius said; he was holding Remus' note.

"I-- yes, well. There was something important I had to do."

He was frowning. "The MLE didn't want a statement from me, too?"

"Hmm? Oh, no-- well, yes, probably. I didn't actually talk to them." Remus felt suddenly very, very unsure of himself. "I, well. I resigned. As your handler, that is. They actually sort of gave me a promotion."

"Why would you do that?"

Sirius was wearing Remus' clothes, and it took him a long few seconds to work through that before he was capable of giving a response. "Well, the DoM doesn't precisely condone relationships between handlers and assets. It does happen occasionally, of course, but--" Remus had to stop because Sirius was abruptly standing, close enough to reach out and touch. And Remus could smell him. The same engine and sandalwood and mint smell he had used to track him in the club, but overlaid, now, with Remus' own.

Any doubts Remus had evaporated, possibly from the sheer heat of his arousal. He surged forward and was highly gratified, highly relieved, when Sirius' mouth met his halfway.

They were probably both insane. It was probably just the adrenalin. Probably, it would never last. Probably. Stupid word.


End file.
